The present invention relates to a method of transmitting an IP (Internet Protocol) address establishment control message applicable to a broadband wireless access system, and more particularly, to a method of transmitting a message in broadcast or multicast format for address establishment to support Mobile IPv4 and Mobile IPv6. Also, the present invention method supports a Mobile IPv4 and IPv6 mobile station that may use idle mode to minimize its power consumption.
Considering the communication protocols related to wireless (radio) access systems, at the network layer, to allow proper data packet communication via the Internet, an Internet Protocol (IP) provides the necessary addressing and routing information for the packets. Here, each device (e.g., user terminal, mobile handset, wireless connectivity device, mobile subscriber station (MSS), etc.) connected via the Internet requires the establishment of a unique IP address in order for that device to be properly identified and distinguished from other devices.
The Internet Protocols referred to as IP version 4 (IPv4) and IP version 6 (IPv6) have been developed. By employing 32-bit addresses, IPv4 has been found to have limitations because of the increasing popularity of Internet communications, whereby each device connected with the Internet needs its own unique IP address. As such, because the availability of 32-bit addresses would soon be exhausted, an enhancement was developed, namely, IPv6, which employs 128-bit addresses. Among such Internet Protocols, an example used in supporting the mobility aspects of user devices (e.g., user terminal, mobile handset, wireless connectivity device, mobile subscriber station (MSS), etc.) may be referred to as Mobility IPv4.
Many wireless networks and devices still employ IPv4 addressing and do not support IPv6 addressing. As future networks and devices are being developed to support only IPv6, and until all networks and devices transition from IPv4 addressing to IPv6 addressing, an interim solution that allows networks and devices to concurrently support both IPv4 and IPv6 is desirable and necessary.
A network that supports Mobile IPv4 comprises a home agent (HA), a foreign agent (FA) and a mobile station.
The Mobile IPv4 operation is as follows. When a mobile node receives an agent advertisement message and determined whether it is located in its home network or in an external network (e.g., a foreign network). Also, a Care-of-Address (CoA) obtained from the foreign network is registered at the home agent (HA).
Table 1 shows an example of an agent advertisement message that is broadcast with respect to Mobile IPv4. When information related to the foreign agent or home agent (FA/HA) is broadcast from the mobile IP to the mobile station, the agent advertisement message shown in the following Table 1 may be used.
TABLE 1Vers = 4IHLType of ServiceTotal LengthIP HeaderIdentificationFragmentOffset[RFC791]Time toProtocol =Header ChecksumLive = 1ICMPSource Address = home and/or foreign agent's address on this linkDestination Address = 255.255.255.255 (broadcast) or224.0.0.1 (multicast)Type = 9CodeChecksumICMPNum AddrsAddrs EntryLife Time (of this Advertisement)RouterSizeAdvertisementRouter Address [1][RFC1256]Router Level [1]Router Address [2]Router Level [2]—Type = 16LengthSequence NumberMobility Agent(maximum) Registration LifetimeRBHFMGVreservedAdvertisementCare-of-Address [1]ExtensionCare-of-Address [2][RFC2002]—Type = 19LengthPrefixPrefixPrefix-LengthLength [1]Length [1]Extension[RFC2002]
In Mobile IPv4 Stateless Address Autoconfiguration, a method of address establishment based upon assistance from the base station is as follows.
First, the host (mobile station) uses a FE80::/64, which is a link-local prefix, and a 48-bit interface identifier in order to induce a temporary link-local address. Also, for checking the uniqueness of the temporary link-local address, a neighbor solicitation message is broadcast to the network in order to perform duplicate address detection, and if the temporary link-local address is not a duplicate, then a router solicitation message is transmitted. Additionally, a router advertisement message is received to induce a global address.
TABLE 2TypeCodeChecksumReservedTarget AddressOptions . . .
Table 3 shows an example of a neighbor advertisement message for IPv6.
TABLE 3TypeCodeChecksumRSOReservedTarget AddressOptions
Table 4 shows an example of a router solicitation message for IPv6.
TABLE 4TypeCodeChecksumReservedOptions . . .
Table 5 shows an example of a router advertisement for IPv6.
TABLE 5TypeCodeChecksumCurHop LimitMOReservedRouter LifetimeReachable TimeRetrans TimerOptions . . .
Table 6 shows an example of a 16-bit connection identifier (CID) defined in a broadband wireless access system of the related art.
TABLE 6CIDValueDescriptionInitial0x0000Used by SS and BS during initialRangingranging processBasic CID0x0001-mThe same value is assigned to boththe DL and UL connectionPrimarym+1-2mThe same value is assigned to bothManagementthe DL and UL connectionTransport2m+1-0xFE9FFor the secondary managementCIDs andconnection, the same value isSecondaryassigned to both the DL and ULMgt CIDsconnectionMulticast0xFEA0-0xFEFEFor the DL multicast service, the sameCIDsvalue is assigned to all MSSs on thesame channel that participate in theconnectionAAS initial0xFEFFA BS supporting AAS shall use thisranging CIDCID when allocating an Initial Rangingperiod for AAS devicesMulticast0xFF00-0xFFFDA SS may be included in one or morepollingmulticast polling groups for theCIDspurposes of obtaining bandwidth viapollingPadding CID0xFFEUsed for transmission of paddinginformation by SS and BSBroadcast0xFFFUsed for broadcast information that isCIDtransmitted on a DL to all SS
The above connection identifier is a unidirectional medium access control (MAC) layer address that identifies the connection of the equivalent peer entities within the MAC layer of the base station and of the mobile station, and each connection comprises the following.
A basic connection is established during ranging, and refers to the connection used for transmitting MAC management messages that are sensitive to delays. A primary connection refers to a connection established during ranging for transmitting MAC management messages that are not sensitive to delays. A secondary connection refers to a connection used for transmitting standard-based messages (e.g., DHCP, TFTP, etc.). Also, a transport connection is a connection used for transmitting user data.
FIG. 1 is an exemplary flow chart showing the procedures for initializing a mobile station in a broadband wireless access system. Referring to FIG. 1, when the initial power of the mobile station is turned on, the downlink channels are searched and uplink (UL) and downlink (DL) synchronizations with the base station are obtained (S111). Also, ranging is performed with the base station to adjust the uplink transmit parameters (S112), a basic management connection identifier and a first management connection identifier are allocated and received from the base station in order to negotiate the basic functions with the base station (S113). After performing authentication for the mobile station (S114), the mobile station is registered with the base station (S115). The mobile station being managed with an Internet Protocol (IP), is allocated a secondary management connection indicator by the base station and establishes an IP connection through that second management connection identifier (S116). Also, the current date and time are set (S117). The content file of the mobile station is downloaded from the TFTP server through the second management connection identifier (S118), and a connection is established for the service that was prepared (S119).
The IP connection establishment procedures using Mobile IPv4 or IPv6 according to the related art will now be explained.
First, the connection establishment procedures using Mobile IPv4 are as follows. For the IP currently used in most Internet environments, it is assumed that an IP address can be used to uniquely identify the access point of a node (host or router). In this case, for any node to receive a datagram transmitted thereto, it must be located within a network that includes its IP address. Thus, a datagram cannot be transmitted to any node that is not located within a network that includes its IP address.
In order to allow a node to change its access point while maintaining communication, one of the following two methods should be used. First, the node must change its IP address whenever its access point is changed, or second, the address of the host that moved must be transmitted to the entire Internet.
Both of these methods have problems. Namely, in the first method, when the node location changes, maintaining the connection between the transport layer and the upper layers of the node are difficult. Also, in the second method, actual implementation will be difficult when assuming that the number of moving nodes will increase. Accordingly, a more extended technique is required to support the mobility of the nodes in the Internet, and one method of supporting such mobility is Mobile IP.
FIG. 2 depicts an example of a network that supports Mobile IP. As shown in FIG. 2, a network that supports Mobile IP basically comprises a home agent (HA) (21), a foreign agent (FA) (22) and a mobile node (23).
The HA and FA are nodes for transmitting a datagram to the mobile node (23). When the mobile node (23) is in communication with a correspondent node (24), upon moving from a home network to a foreign network, procedures to support his are needed. The Mobile IP operates through the following procedures.
First, the mobile node (23) performs procedures to discover an agent. Namely, in order to inform of its existence, the mobile node has an agent or a mobility agent (which is a foreign agent) that employs a method of using an agent advertisement message, which corresponds to the Internet Control Message Protocol (ICMP) router discovery method used when an Internet host wishes to discover a router in the existing Internet procedures. Optionally, the mobile node (23) uses an agent obtaining message to obtain the agent advertisement message. The mobile node (23) receiving the agent advertisement message determines whether it is within its home network.
Also, is the mobile node (23) determines that it is in a foreign network, the Care-of-Address (COA) of the mobile node is registered in the HA (21). Namely, through the agent discovery procedure above, if the mobile node determines that it is in a foreign network, the mobile node and the HA exchange registration request and response messages to register the COA of the mobile node (23).
For the COA, two methods can be used. The first being a foreign agent COA that uses the FA (22) as the COA of the mobile node, and the second being a Co-located COA that allocates temporary IP addresses to the mobile node by a Dynamic Host Configuration Protocol (DHCP). These registered messages employ the User Datagram Protocol (UDP) port number 434 and includes the COA and lifetime of the mobile node.
The related art operation method according to the IPv6 based Stateless Address Autoconfiguration will now be explained. The host (mobile station) uses a FE80::/64, which is a link-local prefix, and a 64-bit interface identifier in order to induce a temporary link-local address. Also, to check the uniqueness of the induced temporary link-local address, a neighbor solicitation message is broadcast to the network to perform duplicate address detection. As a result of the check, if there are duplicate addresses, a neighbor advertisement response message is transmitted from the duplicate host.
As a result of the check, if there are no duplicate addresses, the host (mobile station) transmits a router solicitation message. Also, the received router advertisement message is used to induce a global address.
FIG. 3 shows a method for supporting an agent advertisement of Mobile IPv4 and a router advertisement of Mobile IPv6 in a broadband wireless access system.
As shown in FIG. 3, the base station (32) receives a Mobile IPv4 agent advertisement or a Mobile IPv6 router advertisement that is broadcast from the network (31), and the base station employs a secondary management connection for transmitting these to each mobile station in unicast. Here, the base station allocates a secondary management connection identifier during the procedure when the mobile station registers with the network.
In the broadband wireless access system of the related art, the secondary management connection is used to individually transmit to all mobile stations (31) of the current base station (32), the Mobile IPv4 agent advertisement or the Mobile IPv6 router advertisement that are broadcast from the network. However, even though the agent advertisement and the router advertisement are messages that are commonly broadcast to all mobile stations, such are individually transmitted, which leads to the problem of wasting radio resources.
In a broadband wireless access system, an idle mode of the mobile station is supported in order to minimize power consumption. During idle mode, the mobile station does not need to perform handoff procedures when moving between base stations within the same paging zone. Thus, because the mobile station need not transmit uplink information for handoff procedures, the power consumption needed thereof can be saved.
A general idle mode operation can be summarized as follows.
A paging zone refers to an overall region that is handled by a plurality of base stations called a paging group, and the base stations included within the same paging zone have the same paging cycle and paging offset values.
The mobile terminal can request the base station for change into idle mode, and the base station can change the corresponding mobile station into idle mode by delivering its paging zone ID, and the paging cycle and paging offset associated thereto.
During idle mode, it is possible for the base station to determine whether to maintain or end its idle mode through the paging that is delivered in broadcast format from the base station at each paging cycle that was agreed upon. When a mobile station in idle mode has traffic that needs to be delivered, the mobile station may end idle mode at any time. When a mobile station in idle mode has traffic that needs to be delivered, the base station may make the mobile station end its idle mode through paging. If a mobile station in idle mode does not receive paging within the set time period due to reasons such as moving to a different paging zone, losing synchronization, etc., the mobile station ends its idle mode.
In summary, as long as there is no data to be received or transmitted, a mobile station that entered idle mode can move freely within the same paging zone without performing handoff procedures by properly receiving periodic paging.
The procedures for a fixed/mobile station changing into idle mode are as follows.
1) The fixed/mobile station delivers to the service base station an idle mode request message in order to change into idle mode.
2) The service base station delivers a paging group ID, paging cycle and paging offset values to the fixed/mobile station through an idle mode response message, and the connection information with the fixed/mobile station, the radio resources allocated to the mobile station, etc. are released.
The following Table 7 shows an example of a message that the fixed/mobile station sends to the base station to request idle mode, by using an existing registration release request (DREG-REQ) message.
TABLE 7DREG-REQ messageSyntaxSizeNotesDREG-REQ messageformat ( ) {Management message8 bitstype = 49De-registration_Request—8 bits0x00 = SS de-registration requestCodefrom BS and network0x01 = request for MSSde-registration from Service BSand initiation of MSS IdleMode0x02-0xFF = ReservedTLV encoded parametersvariable}
If the De-registration_Request_Code of the DREG-REQ is set to 0x01 (request to initiate Idle Mode), the following data is included in the DREG-REQ message and delivered to the fixed/mobile station.
TABLE 8TLV encoding of DREG-REQ messageNameTypeLengthValuePaging?2Requested cycle in which the pagingCyclemessage is transmitted within the pagingRequestgroupIdlenn1MSS request for Paging Controller retentionModeof network re-entry related MACRetainmanagement message MSS service andInfor-operational information to expedite futuremationnetwork re-entry from Idle Mode. For each bitlocation, a value of ‘0’ indicates theinformation associated with the specifiedMAC management message is notrequested to be retained and managed, avalue of ‘1’ indicates the information isrequested to be retained and managed.Bit #0: Retain MSS service and operationalinformation associated with SBC-REQ/RSPMAC management messagesBit #1: Retain MSS service and operationalinformation associated with PKM-REQ-RSPMAC management messagesBit #2: Retain MSS service and operationalinformation associated with PKM-REQ-RSPMAC managementBit #3: Retain MSS service and operationalinformation associated with NetworkAddressBit #4: Retain MSS service and operationalinformation associated with Time of DayAcquisitionBit #5: Retain MSS service and operationalinformation associated with TFTP MACmanagement messagesBit #6: Retain MSS service and operationalinformation associated with Full service(MAC state machines, CS classifierinformation, etc.)
The following Table 9 shows an example of an idle more response message that the base station sends to the fixed/mobile station, by using an existing registration release command (DREG-CMD) message.
TABLE 9DREG-CMD messageSyntaxSizeNotesDREG_CMD_Message_Format( ) {Management Message Type = 298 bitsAction Code8 bitsTLV encoded parametersvariable}
The following Table 10 shows an example of the action code that may be used for the DREG-CMD message.
TABLE 10DREG-CMD Action CodeAction CodeAction0x00SS shall leave the current channel and attempt to accessanother channel0x01SS shall listen to the current channel but shall not transmituntil an RES-CMD message or DREG_CMD with ActionCode 0x00 is received0x02SS shall listen to the current channel but only transmit onthe Basic, Primary Management, and SecondaryManagement Connections0x03SS shall return to normal operation and may transmit onany of its active connections0x04SS shall terminate current Normal Operations with the BS;the BS shall transmit this action code only in response toany SS DREG-REQ0x05Require MSS de-registration from Serving BS and requestinitiation of MSS Idle Mode0x06The MSS may retransmit the DRGE-REQ message after thetime duration (REQ-duration) given by0x07The MSS shall not retransmit the DREG-REQ message andshall wait for the DREG-CMD message0x08-0xFFReserved
If the DREG_CMD Action Code is set to 0x005 (allow Idle Mode), the following information is included in the DREG-CMD message and delivered to the fixed/mobile station.
TABLE 11DREG-CMD message TLV encodingNameTypeLengthValuePaging?4Bits15:0 - PAGING_CYCLE-cycle in whichInfor-the paging message is transmitted within themationpaging groupBits 23:16 - PAGING_OFFSET -determines the frame within the cycle inwhich the paging message is transmitted.Must be smaller the PAGING_CYCLE valueBits 31:24 - Paging-group-ID - ID of thepaging group the MSS is assigned toREQ-?1Waiting value for the DREG-REQ messagedurationre-transmission (Measured in frames)Pagingoo6This is a logical network identifier for theCon-Serving BS or other network entity retainingtrol-MSS service and operational informationlerand/or administering paging activity for theIDMSS while in Idle ModeIdlepp1Idle Mode Retain Information is provided asModepart of this message is indicative only.RetainNetwork re-entry from Idle Mode processInfor-requirements may change at time of actualmationre-entry. For each Bit location, a value of ‘0’indicates the information for the associatedre-entry management messages shall not beretained and managed, a value of ‘1’indicates the information for the associatedre-entry management message shall beretained and managedBit #0: Retain MSS service and operationalinformation associated with SBC-REQ/RSPMAC management messagesBit #1: Retain MSS service and operationalinformation associated with PKM-REQ/RSPMAC management messagesBit #2: Retain MSS service and operationalinformation associated with REG-REQ/RSPMAC management messagesBit #3: Retain MSS service and operationalinformation associated with NetworkAddressBit #4: Retain MSS service and operationalinformation associated with Time of DayBit #5: Retain MSS service and operationalinformation associated with TFTP MACmanagement messagesBit #6: Retain MSS service and operationalinformation associated with Full service(MAC state machines, CS classifierinformation, etc.)
3) The base station informs that MAC address of the fixed/mobile station that changes into idle mode to all base stations in its paging group to allow paging of the fixed/mobile station by using the same paging cycle (PAGING_CYCLE, PAGING OFFSET).
4) The fixed/mobile station that has received permission to change into idle mode through the idle mode response message, determines through the paging message delivered in broadcast format from the base station according to the paging cycle, whether there is any downlink traffic to be delivered, whether ranging needs to be performed, or whether idle mode state is to be maintained.
The following Table 12 shows an example of a paging announce message that the base station (that permitted the fixed/mobile station to transition into idle mode) delivers to the paging controller or to all base stations within the same paging zone. The base station that permitted idle mode can deliver this message to the paging controller, which forms the message into another format and can deliver it to all base stations within the same paging zone.
TABLE 12Paging announce messageFieldSizeNotesMessage Type 8-bitSender BS-ID48-bitBase station unique identifier (same number as thatbroadcasted on the DL-MAP message)Recipient BD-ID48-bitSet to 0xffffff to indicate broadcastTime Stamp32-bitNumber of milliseconds since midnight GMT (set to0xffffffff to ignore)Num MSS 8-bitNumber of MSSs to pageFor (j = 0; j < NumMSS; j++) {MSS MAC48-bitaddressPaging Group 8-bitThe identifier of the paging group to which the MSSIDbelongsPAGING16-bitMSS PAGING CYCLE parameterCYCLEPAGING 8-bitMSS PAGING OFFSET parameterOFFSETAction Code 3-bit0 = MSS enters Idle Mode1 = MSS exits Idle Mode2 = MSS should be paged to perform ranging toestablish location and acknowledgement message3 = MSS should be paged to enter network4~7 = reservedReserved 5-bit}Security fieldTBDA means to authenticate this messageCRC field32-bitIEEE CRC-32
The following Table 13 shows an example of a paging message received by the fixed/mobile station at certain periods from the base stations of a paging group.
TABLE 13Broadcast format paging messageBS Broadcast Paging (MOB_PAG-ADV) message formatSyntaxSizeNotesMOB_PAG-ADV_Message_Format Management Message Type=?? 8 bits Num_Paging Group IDs 8 bitsNumber of Paging Group IDs in thismessage For             (i=0;i<Num_Paging_Group_IDs; i++) {  Paging Group ID 8 bits } For (j=0; j<Num_MACs; j++) {Number of MSS MAC Addressesin message can be determinedfrom the length of the message(found in the generic MACheader)  MSS MAC Address hash24 bitsThe hash is obtained bycomputing a CRC24 on the MSS48-bit MAC address. Thepolynomial for the calculation is0x864CFB  Action Code 2 bitsPaging action instruction to MSS00= No action required01= Perform Ranging to establishlocation and acknowledgemessage10= Enter network11= reserved  Reserved 6 bits }}
5) When the fixed/mobile station receives from the paging message that there is downlink traffic, the idle mode state is ended and the downlink data traffic is received upon re-registration with the network.
6) When the idle mode state is ended and upon re-registration with the network, ranging is used to re-register with the network.
The following Table 14 shows a ranging response message that is transmitted in response to the ranging request message, and Table 15 shows the information that is added to the ranging response when location update is performed or upon re-registration with the network after idle mode is ended. Through this, the base station informs of the valid data maintained at the network, such that the steps that may be omitted when the mobile/fixed station re-registers with the network can be known.
TABLE 14RNG-RSP messageSyntaxSizeNotesRNG-RSP_Message_Format( ) { Management Message8 bitsType = 5 Uplink Channel ID8 bits TLV Encoded InformationvariableTLV specific}
TABLE 15Ranging response (RNG-RSP) TLV messageHOnn1For each Bit location, a value of ‘0’ indicates thatProcessassociated re-entry management messages shall beOptimizationrequired, a value of ‘1’ indicates that re-entrymanagement messages may be omitted. Regardlessof the HO Process Optimization TLV settings, theTarget BS may send unsolicited SBC-RSP and/orREG_RSP management messagesBit #0: Omit SBC-REQ/RSP management messagesduring current re-entry processingBit #1: Omit PKM_REQ/RSP management messagesduring current re-entry processingBit #2: Omit REG-REQ/RSP management messagesduring current re-entry processingBit #3: Omit Network Address Acquisition managementmessages during current re-entry processingBit #4: Omit Time of Day Acquisition managementmessages during current re-entry processingBit #5: Omit TFTP management messages duringcurrent re-entry processingBit #6: Full service and operational state transfer irsharing between Serving BS and Target BS (ARQ,timers, counters, MAC state machines, etc.)Bit #7: Post-HO re-entry MSS DL data pending at Target BSHO ID1The identifier assigned to a MSS during HO by a TargetBSLocation10x00= Failure of Location Update. The MSS shallUpdateperform Network Re-entry from Idle ModeResponse0X01= Success of Location Update0x10, 0x11: ReservedPaging4Paging Information shall only be included if LocationInformationUpdate Response=0x01 and if Paging Information haschangedBits15:0 - PAGING_CYCLE-cycle in which the pagingmessage is transmitted within the paging groupBits 23:16 - PAGING_OFFSET - determines the framewithin the cycle in which the paging message istransmitted. Must be smaller the PAGING_CYCLEvalueBits 31:24 - Paging-group-ID - ID of the paging group the MSSis assigned toPaging6This is a logical network identifier for the Serving BS orControllerother network entity retaining MSS service andIDoperational information and/or administering pagingactivity for the MSS while in Idle Mode. PagingController ID shall only be included if Location UpdateResponse=0x01 and if Paging Controller ID haschanged
7) Other than the method above, the fixed/mobile station performs location update through ranging at the point of time corresponding to the update conditions for location update, and the messages in the above Tables 7 and 8 are used. The location update conditions include when the paging zone is changed, when the timer has expired, etc.
8) If the paging message instructs the fixed/mobile station no to take any action, the idle mode state is maintained without any particular action being taken.
9) If the fixed/mobile station has uplink traffic or downlink traffic, or if the idle mode is ended because the paging group has been passed to another base station, the base station informs this to the other base stations within the same paging group, to allow the corresponding fixed/mobile station to be deleted from the list of idle mode fixed/mobile stations.
Except for the above situations where the idle mode mobile station performs location update or when downlink traffic or uplink traffic is generated, the mobile station only performs the procedures to receive paging messages periodically transmitted from the base station, such that free movement within the same paging zone is guaranteed without performing handover procedures, to thus minimize power consumption of the mobile station.
In the related art when changing into idle mode, the mobile station can request in the idle mode request message the management resource information that the base station wishes to maintain, and the base station, through the idle mode response message, can inform the management resource information to be maintained after the mobile station changed into idle mode. Here, through the exchange of idle mode request and response messages, the IP address information of the mobile station can be maintained by the base station after the mobile station changes into idle mode.
By periodically receiving an agent advertisement message and a router advertisement message that are transmitted from the network, the mobile station using Mobile IPv4 and IPv6 must update the validity of the IP that it maintains, but a mobile station in idle mode only performs operations for receiving paging messages and thus cannot receive control messages that are broadcast periodically by the network. An idle mode mobile station that did not receive an agent advertisement message and a router advertisement message, can delivers agent solicitation and router solicitation messages to request transmission of agent advertisement and router advertisement messages, but to do so, the idle mode must be ended. As such, even if the mobile station changed into idle mode to save power, its idle mode is ended every time it cannot receive a control message that is periodically transmitted from the network, and thus the problem of not achieving the effect of minimizing power consumption for changing into idle mode occurs.
Accordingly, the present invention provides a method to allow\reception of agent advertisement messages and router advertisement messages that are broadcast from the network, even when the Mobile IPv4 and IPv6 mobile station changes into idle mode, to allow updating of the validity of the IP maintained by the mobile station while minimizing power consumption.